The invention relates to a crank drive for a material feeder on a machine tool, in particular an automatic punching and bending tool, comprising a crank disc revolving at constant speed round a crank disc axis in a stationary bearing arrangement and a crank pin which is mounted by means of a slide arrangement on the crank disc and of which the eccentricity is adjustable relative to the crank disc axis, wherein, for adjustment of the eccentricity of the crank pin, on the one hand a basic eccentricity setting device actuated by external action is provided and, on the other hand, an eccentricity correcting device which is dependent on the rotational angle, i.e. dependent on the respective local angular setting of the crank disc, is provided.